Kilograms
The kg is defined as being equal to the mass of the International Prototype of the Kilogram (IPK), a block of platinum-iridium alloy manufactured in 1889 and stored at the International Bureau of Weights and Measures in Sèvres, France.
It is the only SI unit that is defined by a physical object rather than a fundamental physical property that can be reproduced in laboratories.
Ton
There are three types of ton- long ton, short ton and metric tonne. Please select a more specific unit.